You had a grueling workout yesterday–or, at least, it certainly seems so. Hitting the gym for the first time in months leaves your hamstrings sore and your hip clicking slightly, and no, that shoulder injury from a while back definitely hasn’t healed on its own. And your first thought after waking up stiff and sore is… Go freeze yourself?

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Freezing isn’t the right word, Joanna Fryben chides me, because there’s actually none of that in whole-body cryotherapy. “It’s actually quite opposite,” she says. “The cold just touches the body.”

But the 39-year-old Fryben, CEO of New York-based KryoLife, allows that it’s a popular misconception–and it’s easy to see why. After all, cryotherapy sounds like something out of a science-fiction novel. But the procedure–little-known in the U.S., though popular in Europe–has been slowly making inroads among body-conscious consumers throughout southern California and, more recently, New York City.

Whole-body cryotherapy is the practice of chilling the skin to just above freezing for approximately three minutes. Some patients are encased from the shoulders down in a cryosauna, a metal tube where temperatures drop as low as -256 degrees Fahrenheit. Others stroll into cryochambers, which are essentially walk-in freezers, surrounded head-to-toe at temperatures ranging from -112 to -180 degrees. It’s essentially an ice bath on steroids, in which the cold decreases inflammation in joints and muscles. It can also help encourage the growth of healthy skin cells, cryotherapists say, and improve the dexterity of existing cells.

Therein lies the opportunity of cryotherapy, a procedure whose origins date back several decades–because from serums and elixirs to peels and injections, the anti-aging industry is a gold mine that’s only going to yield more riches as health-driven Millennials join Baby Boomers who refuse to take aging sitting down. By 2019, the anti-aging market will be worth $191.7 billion, up from the 2013 estimate of $122.3 billion, according to Transparency Market Research.

What’s more, the practice already has a raft of celebrity clients who can help raise cryotherapy’s awareness. Kobe Bryant has used it to assist his recovery from knee surgeries and postgame aches and pains; the NBA’s Phoenix Suns have a team unit for players to use. Actors such as Jessica Alba and Jennifer Aniston use the treatment for the beautification that skin-cell renewal might provide.

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First, a changing room, where you put on a bathrobe, heavy mittens, extra-dry socks and slippers. Then, the chamber. Your first thought is pretty obvious: It’s really, really cold. Many will cut their first treatment short because they just can’t take it for that long. At this particular moment in time, three minutes feels like an eternity.

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These big names are hardly the first to use whole-body cryotherapy, which was invented by Japan’s Dr. Toshima Yamauchi in 1978 in an attempt to treat rheumatoid arthritis. It’s commonplace in Europe, where much of the equipment used already has European Medical Device Approval and UL listing. Fryben discovered cryotherapy in her native Poland after it was part of her mother’s post-surgery physical therapy. Kevin Kramer, the co-founder and COO of the California-based U.S. Cryotherapy, discovered it in 2009 through his father’s neighbor in Prague, Olympic gymnast Denisa Baresova.

Two years later, the 46-year-old Kramer’s company was off the ground–indicative of the rapid spread in the United States since the country’s first whole-body cryotherapy location Millennium ICE opened in 2008 in Dallas. It’s led to a veritable rush of American cryo-preneurs are trying to grab distribution and franchising rights before others can get into the game.

The biggest obstacle: Cryotherapy lacks Food and Drug Administration approval, which can be a deterrent for some consumers. “The medical community is very skeptical naturally, until there’s FDA-approved indication and a vast body of clinical data and support here in the United States,” says Kramer. “People just need to understand the processes, the mode of action, safety profile, those kinds of things that are really critical in the U.S. marketplace.”

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As it turns out, three minutes goes by quickly, especially when you find ways to keep your mind occupied. Sure, you can’t stop your legs from shaking, and you might no longer be able to feel your knees. But you start to feel normal just minutes after you put your clothes back on. Now an exercise bike awaits, because you need to get that blood flowing back to your joints.

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To Kramer, cryotherapy is purely an anti-inflammation mechanism; the treatment does nothing more than enhance circulation of oxygenated blood. At the other extreme, Fryben promotes it as a larger holistic treatment that can alleviate depression, cause weight loss and even eliminate acne.

The middle ground is occupied by Dr. Jonas Kuehne, co-founder and medical director of the Hollywood-based Cryohealthcare. Part of the fight-or-flight reaction involves boosting metabolic rates, he says, so the possibility of weight loss assistance is real. But he’s careful to put emphasis on assistance. “I would not promote it as a weight loss treatment, per se,” he says. “But people, without changing really any parameters, do notice a very nice, gradual weight loss.”

Kuehne, who graduated from the UCLA School of Medicine in 2003 and split his medical residency between the United States and Germany, explains that whole-body cryotherapy does cause the brain to release endorphins, resulting in a temporary runner’s high–but it’s no magic depression cure. And while flash-freezing the skin and underlying tissue can be beneficial–even helping treat inflammatory skin disorders like psoriasis–cryotherapy won’t be replacing Proactiv anytime soon. “You won’t go within one treatment and see a dramatic difference,” he says. “It takes some time.”

At Kryolife’s Midtown Manhattan location, New Yorkers can experience the benefits of the icy therapy for $90 a session or $700 for an unlimited pass. In contrast, both Kuehne and Kramer use business models that promote a series of visits over one-offs. Kuehne’s Cryohealthcare, for example, recommends 6-10 visits for most conditions before patients can start to space them out.

“It’s the way that it needs to be to really treat people to get the clinical outcomes that we’re looking for,” Kramer says. “You just can’t get it in two or three treatments, even though it’s been hyped as such a treatment. It’s not.”

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As you leave the facility, you marvel–not at how different you feel, but at how much you feel the same. But over the rest of the day, you start to realize: Your hamstrings are loosening. Your hip is clicking less. Your shoulder is a little easier to massage. It’s only your first visit–but maybe it’s helping after all.